This paper highlights our work to establish a new class of macrocycles based on Schiff base condensation chemistry. The chemistry of a series of azomethine macrocycles, with selenium/tellurium atoms in o-positions with respect to the CN bond is discussed. These are the first Schiff base macrocycles to incorporate selenium or tellurium atom in the ring. The strong stabilization of the 10-E-3 (E = Se/Te) structures of these macrocycles by E-N coordination permits the access to these novel macrocycles by [2+2] template-free condensation of bis(aldehyde) with primary diamines. The success of cyclization has been confirmed by the usual methods of IR, NMR and X-ray structural determinations. After a brief discussion of the synthetic methods adopted for these macrocycles, their complexing abilities toward different metal ions are covered. The macrocyclic polyamine ligands, derived by reduction of the corresponding Schiff bases, readily form complexes with a range of metal ions. This allows a comparison of the properties of complexes of these ligands with those derived from the Schiff bases containing the same denticity but having a different flexibility. The selena- and tellura-macrocycles reported by other groups in the field are also included for comparison. Also discussed is the anion binding studies of some of these macrocycles.
Bibliographical noteFunding Information:
Aruna and Snigdha are grateful to the Department of Science and Technology (DST), New Delhi, India for financial support under Fast Track for Young Scientist Scheme ( SR/FTP/CS-32/2006 and SR/FTP/CS-85/2007 , respectively). Aruna thanks to BITS, Pilani – K.K. Birla Goa Campus and Singdha to IISER, Kolkota for support. HBS thanks DST for Ramanna fellowship. We thank all our talented coworkers, particularly Dr. Saija C. Menon who was the first one to develop the chemistry described in this paper.
Arunashree Panda received her M.Sc. from Sambalpur University in 1993 and her Ph.D. from Indian Institute of Technology, Bombay in 2000 under the supervision of Prof. H.B. Singh. Subsequently she joined the laboratory of Prof. Philip Power at the University of California, Davis and Prof. Peter Comba at the University of Heidelberg, Germany as an Alexander von Humboldt fellow. Currently she is working as a scientist at Birla Institute of Technology and Science for a DST funded project under the scheme “DST Fast Track for Young Scientist”. Her current research interests are centered on novel selenium/tellurium-containing Schiff base macrocycles and their further chemistry.
- Schiff base